I see this is global problem for this, waiting for while!, anyway there is solution for this at least give information for the users that his item ongoing, or on proccess,
You can make feature like, ”please wait” and loading icon gif, so he can understand that his item or his registeration ongoin,
But whats happen that when user click on ”Submit”, and he wait, he see nothing, then he thought that nothing happen, or he have connection problem, so he keep clicking,
The ad will publich 2, or 3 or 4 times, cuz he clicked sevral time and each time was ”Submit”
I hope you get it,
Thank you